Mooring devices

ABSTRACT

A mooring device includes a tethering cable for tethering a buoyant object, at least one instrument package assembly attached to the buoyant object and through part of which at least the tethering cable passes, connecting cable connecting the buoyant object and the instrument package assembly and formed into a coiled configuration, and means for releasing the instrument package assembly from the buoyant object so that it can be allowed to fall from the buoyant object under its own weight down the tethering cable to a depth predetermined by the available length of the connecting cable. Preferably the arrangement is such that the connecting cable is wrapped round the tethering cable as the instrument package assembly falls and the connecting cable is electrically conductive.

United States Patent Bell et al.

s4] MOORING DEVICES [72] Inventors: Samuel Bell; Leslie Gerald .Bulleu,both of Dartmouth, Nova Scotia, Canada 73 Assignee: Electric s: MusicalIndustries Limited, Middlesex, England [22] Filed: May 7, 1970 [21]Appl. No.: 35,544

[30] Foreign Application Priority Data May 7, 1969 GreatBritain...'....; ..23,l9 l/69 [52] us. Cl. ..9/8R [5 1] Int. Cl. ..B63b21/52 [58] Field of Search-....9/8 R; 114/206 R, 230; 34012; 73/ 170A[56] References Cited UNITED STATES PATENTS 3,377,615 4/1968 Lutes Q...340/2 3,l30,703 4/1964 Thompson ..9/8

[is] 3,705,431 451 Dec. 12, 1972 Primary Examiner-Milton BuchlerAssistant Examiner-Gregory W. O'Connor Attorney-Fleit, Gipple & Jacobson[57] ABSTRACT A mooring device includes a tethering cable for tetheringa buoyant object, at least one instrument package assembly attached tothe buoyant object and through part of which ,at least'the tetheringcable passes, connecting cable connecting the buoyant object and theinstrument package assembly and formed into a coiled configuration, andmeansfor releasing theinstrument package assembly from the buoyantobject so that it can be allowed to fall from the buoyant object underits own weight down the tethering cable to a depth predetermined by theavailable length of the connecting cable. Preferably the arrangement issuch that the connecting cable is wrapped round the tethering cable asthe instrument package assembly falls and the connecting cable iselectrically conductive.

4 Claims, 2 Drawing Figures PATENTED on: I 2 m2 SHEET 1 0F 2 InvonbrsSamuel Bell jails G Bu Hen 'yl filter-n1 PATENTEDHEBIZIQYE 3 705 431SHEET 2 [IF 2 1 v Moonmc unvrcizs The present invention relates tomooring devices,

and is especially applicable to the deployment of an in tethered by aslack upper cable to a submerged float, in

turn tethered by a taut lower-mooring cable. to an anchor on the oceanbed. The purpose of the sub-' merged float, typically implanted at say adepth of 300 feet, is to support the taut lower mooring cable which,typically, could beas'much as 18,000 feet in length, and along which aredeployed one ormore instrument packages. The nature of this typeofsystem dictates that the implantation methods be automatic, andtherefore the lower mooring cable is required to be wrapped round awinch drumion the submerged float, which in turn prohibits theintroduction of instrument packages in the lower mooring cable.

An object of thepresentinvention is to'provide a mooringtievice,especially applicable I to the above mentioned field, whereby the abovementioned disadvantage is substantially overcome.

According to the present invention there is provided a mooring deviceincluding a tethering cable for tethering a buoyant object, at least oneinstrument package deployment-assembly attached to said buoyant objectand through which said tethering cable passes, connecting cable formedin a coiled configuration connecting said buoyant object to aninstrument package contained in said instrument package deploymentassembly, means for releasing said instrument package deploymentassembly from said buoyant object so that said assembly can fall fromsaid buoyant object along said tethering cable, a sensor included insaid assembly for sensing the completion of payout of said connectingcable, anda locking mechanism included in said assembly for locking saidassembly tosaid tethering cable when said sensor provides an indicationthat payout of said connecting cable is complete.

Preferably said connecting cable is wrapped round said tethering cableas said instrument package assembly falls. a

In order that the present invention may be fully understood and readilycarried into effect, it will now be described with reference to theaccompanying drawings of which:

FIG. 1 shows one example of a mooring device according to the presentinvention, and

FIG. 2 shows another view of ,part of the device shown in FIG. 1 tofurther the explanation of its operation.

The example of the present invention to be described is one in which itis required to deploy an instrument package at a selected depth in theocean below a submerged float, and attached to a taut lower mooringcable connecting the submerged float to an ocean-bed anchor. Inaddition, in order that data recorded by the instrument package isavailable at the surface, electrical continuity must be establishedbetween it and a surface buoy. In this example of the present inventionan instrument package deployment assembly is first attached underneaththe submerged float and the instrument package connected to thesubmerged float by means of a coiled length of cable. To establishelectrical continuity between the instrument package and the submergedfloat, and hence to the surface buoy,--the coiled cable is electricallyconductive. When the major mooring has been established, and thesubmerged float has been firmly anchored by the taut lower mooring cable(by means such as are described in US. Pat. application Ser. No. 654,892the instrument package deployment assembly is released from theunderside of thesubmerged float and slides down the lower mooring cabledeploying the conductive cable as it falls and finally coming to rest ata depth predetermined by the length of the coiled conductive cable, atwhich point the'instrument package deployment assembly is locked onto.the lower mooring cable and instruments deployed automatically in anymanner desired.

7 Referencewill now be made to FIGS. 1 and 2, which show an instrumentpackage deployment assembly substantially contained inoutline A, and theunderside of the assembly respectively.

Referring' to FIG. 1 an electrical conductor 1, of ..selec'ted length,comprising the cable from instrument .'package 7 to submerged float 1 9,is wound in the form of a hollow cylinder, or coil, and each winding isencased in a silastic rubber or similar compound. The upper end ofelectrical conductor 1 is terminated by a strain relief device 2, andalso an underwater plug 3 connecting with an underwater electricalsocket 20 located on a submerged float 19. Referring now to FIG. 2 thelower end of electrical conductor 1 is terminated with an underwaterconnector 4 which locates on a socket in an instrument package 7. Thelower. end of electrical conductor 1 is also fitted with two strainrelief devices 21 and 5, one of which, 21, is similar to that on theupper end of electrical conductor 1.

The conductor assembly locates on a circular platform 6 which alsocarries'the instrument package 7, and a center tube 8 in the form of ahollow cylinder extending up through the center of the conductorassembly. A casing 9 in the form of a thin split cylinder is attached tothe'rim of the platform 6 using locking bolts 10, (referring now toFIG. 1) and encloses the conductor assembly. A frusto-conical enclosure11 at the top of the split cylindrical casing 9 is designed to providean annular space between its top and the center tube 8 attached to thecircular base 6. Fitted in this space is a rubber tensioning grommet 12.Fins 13 are attached to the outside of the frusto-conical enclosure 11to ensure a uniform and predictable descent of the whole assembly. Thewhole instrument package deployment assembly is located centrally belowa winch drum 22 carrying the lower mooring cable 23 and is attached tothe underside of submerged float 19 by means of connecting rods 24 whichare connected from float 19 to lugs 25 on casing 9. The attachment tolugs 25 is achieved by means of a plug of material soluble in sea waterand is such that the material will only completely dissolve and breakthe attachment until after lower mooring cable 23 is fully paid out andis taut. Prior to instrument package deployment, then, the lower mooringcable 23 pays out through the center tube 8.

After an anchor has reached the sea bed, and all the required mooringcable has been paid out and is taut, the attachment of connecting rods24 to lugs 25 is broken and the instrument package assembly is releasedfrom the underside of submerged float 19 and falls under its own weightdown the lower mooring cable 23. It may alternatively be arranged thatmeans sensitive to pay out of mooring cable 23 are provided which sensewhen cable pay out ceases and cause a connection between float l9 andthe instrument package assembly to be broken, so that the instrumentpackage assembly is released immediately after tethering of float 19 hasbeen achieved. As it falls the electrical conductor 1 pays out from theencapsulated coil within the assembly. The rubber tensioning grommet 12is so arranged that a force of two or three pounds is necessary to payout the electrical conductor 1, and thus as the whole assembly falls theelectrical conductor l is firmly wrapped round the lower mooring cable23.

When the whole instrument deployment assembly reaches the depthdetermined by the length of the electrical conductor 1, the action ofpaying out the last turn of the conductor 1 triggers a lever mechanism14 which in turn activates a spring loaded piston 15 (see FIG. 2) whichlocks the circular platform 6 to the mooring cable 23.

A timed release mechanism 16 operates approximately three hours, afteroperation of the locking, releasing the split cylindrical casing 9 intothe sea. A further release mechanism 17 timed to operate approximatelyone hour after the release of split cylindrical casing 9 then frees agate 18 which allows for the deployment of the instruments from theinstrument package 7 as required. Timed released mechanisms 16 and 17comprise soluble material type timed release mechanisms, that is theattachments are achieved by means of plugs of material soluble in seawater. Typically, instruments such as hydrophones or temperature probesare deployed on self-erecting booms radially to the lower mooring cable23.

The present invention is not limited to the deployment of a singleassembly, indeed several instrument packages may each be deployed totheir own predetermined depths from the one submerged float by means ofseveral instrument package deployment assemblies in tandem, each onebeing deployed to a predetermined depth below the one above it.

What we claim is:

1. A mooring device including a tethering cable for tethering a buoyantobject, at least one instrument package deployment assembly attached tosaid buoyant object and through which said tethering cable passes,connecting cable formed in a coiled configuration connecting saidbuoyant object to an instrument package contained in saidinstrumentpackage deployment assembly means for releasing said instrument packagedeployment assembly from said buoyant object so that said assembly canfall from said buoyant object along said tethering cable, a sensorincluded in said assembly for sensing the completion of payout of saidconnecting cable, and a locking mechanism included in said assembly forlocking said assembly to said tethering cable when said sensor providesan indication that payout of said connecting cable is complete.

2. A mooring device according to claim 1 in which said connecting cablecoils round said tethering cable as said instrument package falls 3. Amooring device according to claim 1 in which said connecting cableincludes at least one electrically conductive core.

4. A mooring device according to claim 1 including a plurality ofinstrument package deployment assemblies threaded on said tetheringcable and connected to said buoyant object by respective connectingcables.

1. A mooring device including a tethering cable for tethering a buoyantobject, at least one instrument package deployment assembly attached tosaid buoyant object and through which said tethering cable passes,connecting cable formed in a coiled configuration connecting saidbuoyant object to an instrument package contained in said instrumentpackage deployment assembly means for releasing said instrument packagedeployment assembly from said buoyant object so that said assembly canfall from said buoyant object along said tethering cable, a sensorincluded in said assembly for sensing the completion of payout of saidconnecting cable, and a locking mechanism included in said assembly forlocking said assembly to said tethering cable when said sensor providesan indication that payout of said connecting cable is complete.
 2. Amooring device according to claim 1 in which said connecting cable coilsround said tethering cable as said instrument package falls.
 3. Amooring device according to claim 1 in which said connecting cableincludes at least one electrically conductive core.
 4. A mooring deviceaccording to claim 1 including a plurality of instrument packagedeployment assemblies threaded on said tethering cable and connected tosaid buoyant object by respective connecting cables.